Production of high wet strength paper



United States PatentO PRODUCTION OF HIGH WET STRENGTH PAPER Thomas M. Laakso and William F. Fowler, Jr., Rochester, N.Y., assiguors to Eastman Kodak Company, Rochester, N .Y., a corporation of New Jersey No Drawing. Application July 7, 1955 Serial No. 520,611

1 Claim. (Cl. 96-85) This invention concerns a method for imparting high wet strength to paper.

Photographic papers for the most part must be capable of withstanding a certain amount of handling while wet due to the requirement that the sensitized coating must be processed in photographic solutions. Consequently, various agents are added to the paper pulp from which photographic paper is made in order to add to the wet strength of the finished photographic paper. Some of these photographic papers have incorporated cationic urea-formaldehyde or melamine-formaldehyde condensates. The wet strength values imparted to the paper using these condensates are sufiiciently high, but it has been found in certain applications that it would be preferable to have a smaller amount of formaldehyde present.

We have discovered a new group of resin intermediates as wet stre'ngtheners for photographic paper which only require the use of very small relative amounts of formaldehyde. These are polyaminotriazole-formaldehyde intermediate resin condensates.

One object of this invention is to provide a photographic paper having high wet strength. Another object of this invention is to provide a formaldehyde-condensate for imparting high wet strength to paper in which a relatively small amount of formaldehyde is used. A further object of this invention is to provide a photographic paper having high wet strength which serves as a suitable support for commercially available tub sizes.

The above objects are obtained by'condensing hydrazine with a dibasic acid or ester thereof to produce the corresponding dihydrazide:

R is (CH in which it may be from 0 to 8.

A dihydrazide is then heated in the presence of a small amount of aqueous hydrazine to produce a condensation polymer containing as the recurring linkage a 4-amin0- 1.2.4-triazole ring:

2,928,736 Patented Mar. 15, 1960 p CC EXAMPLE I-A Preparation of butane-1,4-dicarbohydrazide Two thousand eighty-eight grams( 12 moles) of methyl adipate, 1200 ml. (24 moles) of hydrazine hydrate (64 percent) and 2500 ml. of methanol were refluxed overnight on a steam bath. After cooling to room temperature, the crystalline product was filtered by suction, washed well with methanol, and dried.

The yield of snow-white crystals of butane-1,4-dicarbohydrazide, M.P. 181-182 C., was 95 percent of the theoretical value.

EXAMPLE I-B Preparation of Polytetramethylene-4-aminotriazole Six hundred and twenty grams of butane-1,4-dicarbohydrazide and 50 ml. of hydrazine hydrate (64 percent) were heated in an autoclave for one hour at 220 C. The pressure was then released to 200 pounds per square inch. The temperature was maintained at 220 but at regular intervals the pressure was released to 200 pounds per square inch over a period of about 3' hours.

The product was a white solid having an intrinsic viscosity of 0.32 in phenol-tetrachloroethane and a melting point of 315 C.

- EXAMPLE I-C Preparation of polytetramethylene-4-aminotriazoleformaldehyde intermediate resin acid solution One hundred grams of polytetramethylene-4-aminotriazole powder was dissolved in 0.5040 normal hydrochloric acid. This solution was filtered to remove a small amount of acid-insoluble material. One hundred milliliters of this solution was rapidly agitated mechanically while 1.2 ml. of 18-20 percent aqueous formaldehyde solutiouwas added. A sharp rise in viscosity of the mix was observed within one hours standing at room temper- I ature, after which time the resin intermediate solution was incorporated into the paper-making pulp slurry.

EXAMPLE II-A Preparation of octane-1,8-dicarbohydrazide Five hundred grams (2.2 moles) of methyl sebacate, 1 1

220 ml. (4.4, moles) of hydrazine hydrate (64 percent) and 500 ml. of methanol were refluxed overnight ona steam bath. After cooling to room temperature, the

crystalline product was filtered by suction, washed well;- with methanol, and dried.

The yield of snow-white crystals of octane-1,8-dicarbo hydrazide, M.P. 184-185.C., was 95.percent of the theoretical value.

("3- R-C O-NH-NHa-H (11-1) H a 0 EXAMPLE II-B Preparation of p0lyoctamethylene-4-aminotriazole Seven hundred and five grams of octane-1,8-dicarbo hydrazide and ml. of hydrazine hydrate (64 percent) f were heated in an autoclave for .one hour at 220? C. The pressure was then released to 200 pounds per square inch. The temperature was maintained at 220 C. but at regular intervals the pressure was released to 200 pounds per square inch over a period of about 3 hours.

The product was a white solid having anintrinsic viscosity of 0.3 to 0.4 in phenol-tetrachloroethane.

Toxeach of twelve difierent samples, of six liters of Jordannedxwater leaf paper slurry containing 2.25; percent pulp were added the chemicals listed. in. the-order added. The mixtureswereeach stirred mechanically for @Wss slih s s aciqslor the r esters), uch s osal ama onia see,

cinic, .glutaric, pimelic, suberie, azelaic, and the dimer 'ized" fatty acids may be employed. The sizing operation; instead of taking place in the pulp slurry, may be done as a tubbing operation subsequent to sheet formation and initial drying on the paper; machine. Tub sizes such as Hercules Aquapel 380, du l fonts Quilo'n. Dew

' Cornings- Siliones and othersrnaybe-used after beater a few'minutes, and made into hand sheets weighing I grams per sheet ona Noble and Wood hand sheet machine. Drying was for 5 minutesat 210-2 20". F. The various chemicals whichN'vere added to the sample are lisfedfin the table which follows, together with observed pH v'alues -atfter each adjdition.

TABLE I.-CHEMICALS ADDED TO aurn'ns or 2.25% PULP 1 swamp .Initlal' Amt; :Amt. Amt. andT-ype. Elna! Np. pH Sizing, A1013, Wet Strengthener pH N-81.. 7.35 None None None V 7. N"82-. 7.25 None None 36 ml. 7% mel.CH' O. '5. N83- 7.40 None None 30 ml. 10% PAT-4CHsO 4. N84 7.40 None None .30,ml.10% PAT8 -CH O 3. N.85.. 7.40; None 11.5 Non 4. N:86 7.40 None 7;0 36 ml. 7% meL-CHrO. 4. N-87 7.40 None 11.5 30 m1.10% Para-c1120--. a. N sst; 7.40 None 11.5 30 m1, 10% PAT 8 O H'z0; 2. -N-s9.. 7.40 141 28.0 'None 4. N 7.40 141 28.0 -36'ml.7% men-onion-.- 4. N;- ;1.4 0 141; 23. 0 3 Oml-.10% ra'r-eomo..- 4. N-92. 1.49 14; t 28.0, so 1.1o% Pans-.0320--. 4.

Non -Identification in detail of chemicals is as .follows:

" Slzlng!=A-solutlon containing 1.9 percent stearlc acld plns 2.2 the stolchlometric amount of an alkali metal hydroxide. l AlCl;-=A lfi percent aqueous solution ol A1Cl3. Mel-C1120 ,Commerclal melamineeformaldehyde methylol-melamine) dissolved in dilute hydrochloric a o1d. PAT-4CH=0?'- -Polyamin rlazole-tormaldehy de res n mterruedlate (essentially trl:

solution prepared as in Example 1, Part C "PAT-B-CHgO=Polyaminotriazole-tormaldehyde resin intermediate solution prepared as'ln EkampleILBartG.

V X MP E 1V Testing of the' paper Each of the sets of hand sheets whose-preparation is described in Example III was testedfor wet strengthand- Valley penetration. Results are tabulated below.

' TABLE 1I.-PHY.SI'CALTEST RESULTS 1 Wetv Valley;

No. Ohemicals hdded to Pulp Strength P epetr a- N-81 None Nil Nil N82 Mel-C1120 only 7.75 Nil N-83- PAT+-CH only 4. 75 Nil N-SL- PAT-S-CHrO only 2. 50- Nil N-85 AlC only 1.00 N l N-86 AlOh+Mel.-OII20 8.75 N l N- A1Cl3+PAT--4CH2O 10.25, -N1l N88 AlCls+PAT8CHrO-- 4.25 Nll N- Stearate size-l-AlCls 1.50 93 N-QO Stoarate size+AlCh+Mel.-CH:O 6.50 2,000

1 Average of 5 measnrementsln all cases;

It may be seen-from an examinationof'TableII that polyaminotriazole formaldehyde intermediates, when.

sizing with. these polyaminotriazole-formaldehyde con;-

densates. It will' bev noted fronythel examples that. in Preparing e po y min a l rform ld hyd resin; intermediate sqlutions that only 2.4 percent of the weight of the resin is formaldehyde :as compared with that incorporated into the sheet when .trimethylol-melamine condensate is used of about 41 7' percent formaldehyde.

' Paper prepared according to our invention is com patible with photographic emulsions containing lightsen- .sitivezsilver halide salts such assilvcr bromide. silver chloride and the like V Paperprepared according to Example I'in whichapolr aminotriazole, was incorporated inthe paper; pulp was:

directlysensitized-with, a washed silverbromide; photo:

tween two wooden blocksthat have been drilled wallow. an. electrolyte (516 ml. distilled water, 24 .K. of NaCl-,

..60 rn l.- glycerine) to contactboth sides-of thepaper simultaneously. over a circular area of approximately one-,inch diameter. A potential is applied that allows, 200. ma. 0t;

current toflow whenno paper sample is present. When. a?

paper sample is mounted in the blocks, the time-in, seconds.

noted fromthe. moment the electrolyte is firstbrought in. contactwith the paper sample until 160 milliamps; off

current flows throughthepaper sample.

The paper was tested, for wet strength. by atwo hour' immersion iu distilled water at room temperature fol:

lowedby measuring the bursting strength in a Minden;-,

paper. testen in. pounds. per, square inch.

We claim:

A; paper havinga. heater sizing including approximately. 2%. (basedf on the bone-dry weight of the pulp);

., of a polyaminotriazole-formaldehyde.condensatetprepared,

' by heating a dihydrazide having the formula a form a polyaminotriazole andcondensing with formalde Leo added toa pulp slurry, will very greatlyjncreasethe wet 1 strength of lordan necl' water lea-f sto'ckl These resinfin with sodium stearate; (as: asiziug; agent-); and; aluminum terrnediates: are mosteefiectivewhen' usedinthe presence ofalurninurn: chloride, but-produce a very large increase: in 'e'tstrength WIienused eitherfalone or inconjunction.

V H -NH cocr1 co NH-NH in which n may be between 0 and 8 with hydrazine to hyde sufiicient only to react with "the primary amino groups, andIa photographic lightsensitive silver halide..

coatingappliedon said sized paper, said sizingimparting high wet strength to'the' paper and being chemically. inactive to deteriorate therlightsensitive chemicals of said coating. 7

References Cited in the file of this patent M UNITED STATES PATENTS 1,370,650 Hoskins Mar. 8, 1921 2,384,369 DAlelio Sept. 4, 1945 2394;289 Boughton 'Feb. 5, 19.46.; 2,447,064.; Gebhart Aug. 17, 1948;: 2,626.;21'4. Osborne" Jan. 20, 1953,; 2,6,65;26 1. Baker Jan. 5', 19,54; 7 2,689,228 Thomas Sept. 14, 1954;; 2.7943737 Lundberg June.4;. 1957 Q naa appearances.

Fisher: Polyaminotriazolesas- Fiber-Forming Ma terials published in .th e lournal of Applied chegusgy, f

volumenti part 4 April 1954; pages-212 2192 

